High speed printing and graph plotting machine



Nov. 8, 1966 J. HIGGINS ETAL 3,283,702

HIGH SPEED PRINTING AND GRAPH PLOTTING MACHINE Filed April 20, 1964 9Sheets-Sheet l N 1966 1.. J. HIGGINS ETAL 3,

HIGH SPEED PRINTING AND GRAPH PLOTTING MACHINE Filed April 20, 1964 9Sheets-Sheet 2 T1 c1131- Z7 9 Sheets-Sheet 4 L. J. HIGGINS ETAL HIGHSPEED PRINTING AND GRAPH PLOTTING MACHINE Nov. 8, 1966 Filed April 20,1964 Nov. 8, 1966 J. HIGGINS ETAL 3,283,702

\ HIGH SPEED PRINTING AND GRAPH PLOTTING MACHINE Filed April 20, 1964 9Sheets-Sheet a I MNN \Qm' QM +l m L L. Qw

United States Patent 3,283,702 HIGH SPEED PRINTING AND GRAPH PLOTTINGMACHINE Leonard J. Higgins, Smithtown, and Harold S. Schwartz,

White Plains, N.Y., and Edward R. Richardson, Philadelphia, Pa.,assignors, by direct and mesne assignments, to Potter'lnstrumentCompany, Inc., Plainview, N.Y., a corporation of New York Filed Apr. 20,1964, Ser. No. 361,303 35 Claims. (Cl. 101-93) This invention relates toapparatus for high speed plotting of curves and graphs along with dataand information and more particularly to an apparatus for plottingcurves and graphs at high speeds in response to digital input signals.

In digital data processing there has been a need for an output apparatuswhich will plot curves and graphs represented by the digital output ofthe computers and other types of data processing equipment. The plottersof the prior art such as XY plotters, electronic beam plotters andelectrostatic plotters are not satisfactory for data processing outputequipment. The XY plotters are not fast enough to handle the output dataat the rate that it is produced by modern data processing equipment andthe electrostatic or electronic beam plotters are not practical becauseof their cost and complexity.

The system of the present invention provides a relatively simple, highspeed plotting apparatus which can also be used to print output data. Inaccordance with the present invention special characters in the form ofdot configurations are raised in relief on a drum which rotates at ahigh speed. Means are provided to select any one of the specialcharacters and to print it on paper. By controlling the selection of thespecial characters to be printed and by controlling the feed of thepaper, any desired curve or graph may be printed out at a high speedwith good resolution. Alpha-numeric characters are also provided on thedrum and may be selected to print output data along with the curves andgraphs.

Accordingly, an object of the present invention is to provide animproved curve and graph plotter.

Another object of the present invention is to provide a high speed curveand graph plotter.

A further object of the present invention is to increase the speed withwhich computer output data representing curves and graphs may beplotted.

A still further object of the present invention is to provide a highspeed curve and graph plotter which will also function to print dataalong with the curves and graphs plotted.

A still further object of the present invention is to provide a plotterwhich will plot curves and graphs represented by digital data with goodresolution.

Further objects and advantages of the present invention will becomereadily apparent as the following detailed description of the inventionunfolds and when taken in conjunction with the drawings wherein:

FIG. 1 schematically illustrates the plotter of the present invention;

FIG. 2 illustrates the print drum of the plotter of the presentinvention;

FIG. 3 is an end view of the print drum of the present inventionillustrating the distribution of the special characters for plottingcurves and graphs;

FIGS. 4-10 illustrate the rows of special characters on the print drumfor plotting curves and graphs;

FIG. 11 shows an example of a curve plotted with the apparatus of thepresent invention in actual size;

FIG. 12 is a block diagram illustrating the circuitry for controllingthe plotting and printing operation in accordance with applied inputdigital data; and

FIGS. 13-18 are block diagrams of subcombinations of the block diagramshown in FIG. 12.

As shown in FIG. 1, the printer plotter of the present inventioncomprises a drum 21, which is rotated on its axis at a high speed, 1200rpm, by a motor 23. As best shown in FIG. 2 the drum has on itscylindrical surface 4 axially disposed rows of characters with the rowsbeing distributed around the circumference drum. All the characters ofany given row are the same, different characters being found indifferent rows. The characters include 26 letters of the alphabet thenumerals zero to nine and other characters needed in printing such aspunctuation marks. These types of characters are referred to asalpha-numeric characters. The characters are raised in relief from thecylindrical surface of the drum so that they may be readily used forprinting as will be described below. In addition to these characters,the drum is provided with 7 rows of special characters for plottingcurves and graphs. These 7 rows of special characters are distributed atregular intervals about the circumference of the drum as is illustratedin FIG. 3, in which the rows of special characters are designated by thereference number 25 and the remaining alpha-numeric character rows aredesignated by the reference number 27. A row of 132 hammers 29, eachactuated by a solenoid 31, are positioned extending axially along thedrum 21. The faces of the hammers 29 are positioned and aligned so thateach row of characters of the drum 21 will sequentially come under thestriking faces of the hammers 29 and the characters of each row willsimultaneously pass under the row of hammer faces. As pointed out above,132 hammers are provided so that there is one hammer for each characterin a row. When a row of characters passes under the row of hammer faces,each character in the row will be opposite the face of a differenthammer. A web of paper 33 on which a curve is to be plotted is fedbetween the row of hammers and the drum 21 by means of a paper feedingmechanism 34. An ink impregnated ribbon 35 is fed between the drum 21and the paper 33. When one of the solenoids 31 is energized it willdrive its hammer against the paper and strike the paper and theimpregnated ribbon against the drum. As a result whatever character onthe drum is beneath the hammer will be printed on the paper at the spotwhere the hammer engaged the paper. By controlling the time that eachhammer is driven against the paper in accordance with the position ofthe drum, any character on the drum may be printed on the paper. Forexample, if it is desired for the character A to be printed by one ofthe hammers 29, the solenoid operating this hammer will be energized asthe drum rotates at a time relative to the position of the drum so thatthe hammer is driven against the paper just when the row of As on thedrum comes under the row of hammers. The energizing voltage is appliedto each hammer in the form of a pulse, which is referred to as a hammerdriving pulse. The hammer driving pulse has to be applied to thesolenoid 31 controlling the hammer under which it is desired to print acharacter before the row of desired characters actually comes under therow of hammers because the hammer 29 will be driven against the paper 33a short interval after the hammer driving pulse is applied to thesolenoid due to the inertia of the hammer and the inductance of thesolenoid. The position which a row of characters occupy when the hammerfiring pulse or pulses must be applied to print one or more charactersin the row is referred to as the print position.

Each character has a field in which it is located. The field of acharacter is defined as the total area which can be occupied by acharacter. In the apparatus of the present invention the characterfields are rectangular.

The special characters for plotting curves and graphs, as illustrated inFIGURES 4 through 10, comprise dots arranged in dilferent configurationsand positions on their fields. Each special character in the row shownin FIG. 4 consists of a single dot in the middle of the left-hand sideof the character field. Each special character in the row shown inFIGURE 5 consists of a single dot in the middle of the character field.Each special character in the row shown in FIG. 6 consists ,of a dot inthe middle of the right-hand side of the char ac r field. Each specialcharacter in the row shown in FIGURE 7 consists ow two dots, onepositioned in the middle of the lefthand side of the character field inthe same position as the dots of the characters shown in FIGURE 4 andthe other positioned in the middle of the character field in the sameposition as the dots of the characters shown in FIGURE 5. Each specialcharacter in the row shown in FIGURE 8 consists of two dots, one in themiddle of the character field in the same position as the dots of thespecial characters shown in FIGURE 5 and one positioned in the middle ofthe right-hand side of the character field in the same position as thedots of the special characters shown in FIGURE 6. Each special characterin the row shown in FIG. 9 consists of two dots, one positioned in themiddle of the left-hand side of the character field in the same positionas the dots of the special character shown in FIG. 4 and the otherpositioned in the middle of the right-hand side of the character fieldin the same position as the dots of the special characters shown in FIG.6. Each special character of the row shown in FIG. 10 consists of threedots arranged horizontally, one positioned in the middle of theleft-hand side of the character field in the same position as the dotsof the special characters shown in FIGURE 4, one positioned in themiddle of the character field in the same position as the dots of thespecial characters shown in FIGURE 5, and one positioned in the middleof the left-hand side of the character field in the same position as thedots of the special characters shown in FIGURE 6.

By selecting the proper ones of the special characters to be printed andby controlling the distance that the paper is fed between printings anydesired graph or curve may be plotted with good resolution. Goodresolution will be obtained horizontally because dots can be printed inany of three horizontally spaced positions in each character field. Goodresolution is obtained vertically in accordance with the presentinvention by feeding the paper in small increments equal to a fractionof the vertical dimension of a character field. The dots of the specialcharacters are spaced horizontally of an inch apart and when a surve isbeing plotted the paper is advanced in increments of of an inch. Withthis arrangement, curves and graphs may be plotted with a resolution toof an inch. An example of a curve plotted with the apparatus of thepresent invention is shown in FIG. 11 in actual size. The increasedresolution is obtained with the present invention because the apparatusof the present invention can print a plurality of character dots atdifferent positions in a space corresponding in size to the field of onecharacter. This characteristic is referred to as subdivided characterfields. It will be apparent that the resolution may be further increasedjust by further subdividing the character fields.

FIG. 12 is a block diagram of electronic circuitry for controlling theenergization of the hammer solenoids to print characters on the drum 21selected in accordance with coded input signals and controlling the feedof the paper on which the characters are printed. Coded binary signalsrepresenting the characters to be printed are applied in parallel oversix input channels designated by the reference number 41. Each row ofcharacters on the drum 21 is represented by a dilferent binary code onthe six input channels 41. The codes representing a line of charactersto be printed are fed in sequence to the circuit at input 41 and storedtemporarily first in an input register 43 and then in a delay linestorage 45. When a whole line of character codes is stored in the delayline storage 45, the characters represented by the codes in the delayline storage are compared with the counts represented by a binarycounter 47. Counter 47 counts pulses from a tone wheel 49 fixed to thedrum as illustrated in FIG. 1. The tone wheel 49 comprises a disc of lowreluctance material, which has radial slots distributed around thecircumference thereof. A transducer 50 positioned adjacent the peripheryof the tone wheel 49 will produce a pulse each time one of the radialslots passes under it. The pulses produced by the transducer 50 areapplied to a channel 53. Accordingly the tone wheel 49 produces onchannel 53 via the transducer 50 one output pulse per row of charactersas the character rows rotate past the hammers 29. A second tone Wheel 51comprising a disc of low reluctance material like the tone wheel 49 buthaving a single radial slot is also fixed to the drum. The tone Wheel 51produces on a channel 55 one output pulse per revolution of the drum bymeans of a transducer 52. The output pulses of the tone wheel 49 arecalled count pulses and the output, pulses of the tone wheel 51 arecalled index pulses. The counter 47 counts the pulses produced onchannel 53 and each index pulse produced on channel 55 will reset thecounter 47 to zero. Thus as each row of characters comes into the printposition a different count will be registered in the counter 47. Eachcharacter code will be identical to the binary code of the countregistered in the counter just before the character represented by suchcharacter code reaches the print position. Therefore, the six-placebinary character code representing a particular character will be thesame as the six-place binary coderegistered in the binary counter 47just before the row of characters represented by the input code comesinto the print position. Each count registered by the counter 47 iscompared with all of the character codes representing the 132 charactersto be printed in one line stored in the delay line storage 45. Each timethat the comparison circuit 57 detects that a code in a delay linestorage 45 is the same as the count registered in the counter 47, itproduces a hit pulse. Each hit pulse produced by the comparison circuit57 means that a character from the row of characters approaching theprint position is to be printed. The column in which the character is tobe printed is determined by the position of the code representing thecharacters in the delay line storage 45. A 132 stage hit register 59stores the hit pulses produced by the comparison circuit 57. The hitregister 59 has a different stage corresponding to each column on thepaper and to each hammer. A selector matrix 61 stores the hit pulsesproduced by the comparison circuit 57 in the stages of the hit registers59 corresponding to the columns in which the characters are to beprinted. The next count pulse produced by the tone wheel 49 increasingthe count in the counter 47 is also applied to a set of gates 63, whichread out the stored pulses from the hit register 59 and apply them tohammer driving pulse generators 64. The generators 64 apply hammerdriving pulses to the solenoids corresponding to the stages in which thehit pulses were stored. The solenoids receiving the driving pulses willthen strike the corresponding hammers against the paper and will causecharacters to be printed in the corresponding columns of the paper. Thecharacters that will be printed will be from the row of characters whichwere approaching the print position when the comparison was made betweenthe contents of the delay line storage 45 and the count registered inthe counter 47. Each time the count registered by the counter 47 ischanged by the application of a count pulse to the counter 47 the entirecontents of the delay line 45 is compared to the new count registered bythe counter 47 and new hit pulses are stored in the hit register 59 sothat the characters selected in each column by the codes stored in thedelay line 45 a stored clock pulse.

will be printed on the line of paper under the hammers. The paper willremain in its position until the drum has made one complete revolutionso that all the rows of characters have had a chance to be printed inthe line heneath'the hammers. In this manner, the character from anyselected row may be printed in any selected column on the line of paperbeneath the hammers. When the drum has completed one revolution and allof the rows on the drum have had a chance to be printed, the paper isadvanced so that a new line of characters may be selected in the samemanner.

A clock pulse is applied at an input channel 71 with each character codeof parallel binary bits applied on input channels 41 from theinformation source. The clock pulse is applied to a gate 73, which willbe enabled by a signal from a flip-flop 75 when the flip-flop 75 is inits A state. The flip-flop 75 will be in its A state when the circuit isin its data insertion phase ready to accept the character codes from theinformation source. When the gate 73 is enabled, each clock pulseapplied over the input 71 will pass through the gate 73 and then througha 1.5-microsecond delay line 77. After passing through delay line 77,each clock pulse will be applied to a set of six gates 79 and willenable these gates. The character codes applied to input channel 41 areapplied to the input register 43 through the gates 79. The clock pulsespassing through the delay line 77 and applied to the gates 79 strobe thecharacter codes into the input register. Thus, character codes can beapplied to the input register only when the flip-flop 75 is in its Astate and only if they are properly accompanied by a clock pulse.

The input register 43 comprises eight ranks of siX stages each. Each ofthe eight ranks is capable of storing one character code. Each charactercode passing through the gates 79 will be stored in a rank of theregister 43 selected by an input counter 81 in accordance with the countregistered thereby. The counter 81, which counts the passing through thedelay line 77, has a capacity of eight different counts, zero to seven,and selects a difierent rank in the input register for each countregistered thereby. As each clock pulse passing through the delay line77 is applied to the counter 81, the count registered by the counter 81will increase incrementally until the count registered by the counter 81reaches 7. The next pulse applied to the counter 81 will recycle thecount registered thereby to zero. Thus the counter 81 will select theranks in the input register in sequence and will cyclically repeat thesequence. Since each clock pulse will incrementally change the countregistered by the counter 81, each character code will be stored in thenext sequential rank in the input register after the rank in which thepreceding character code was registered. :In this manner, the inputregister keeps track of the sequence in which the character codes areapplied to the input channels 41 so that the characters can be arrangedin the same sequence when they are printed.

The clock pulses after passing through the delay line 77 are alsoapplied through another 3-microsecond delay line 83 to a cynchronizer85. The synchronizer 85 also receives pulses from a two-megacycle clockpulse generator 87 and produces one output pulse on a channel 89 foreach clock pulse received from the delay line 83. Thus the pulsesproduced on channel 89 are clock pulses corresponding to the clockpulses accompanying each character code. The synchronizer 85 serves toinsure that each clock pulse produced on channel 89 does not occursimultaneously with a tWo-megacycle clock pulse. The clock pulsesproduced in this manner on channel 89 are applied to the input register43. Each rank of the input register 43 is provided with an additionalflip-flop for storing the clock pulses on channel 89 to indicate that acharacter is stored in that rank. Thus, each rank of the input register43 storing a character code will also have The purpose of this storedclock pulse is to enable the circuit to determine when it has 6 read outall of the stored character codes in the input register.

The character codes stored in the input register 43 are read out fromthe ranks of the register in the same sequence in which they were storedin the input register. Each character code read out from the inputregister 43 is applied directly to the delay line storage 45, in whichthe character codes are stored in the same sequence in which they areread out. The delay line storage comprises six delay channels, each ofwhich provides a 66-microsecond delay. Each six-bit binary charactercode is stored in the delay line storage by applying each bit of thecharacter code simultaneously to the input of a different delay channel.After a character code has been applied to the inputs of the delaychannels it will continuously recirculate in the delay channels untilthe delay line storage is cleared. The two-megacycle clock pulsesproduced by the clock pulse generator 87 are applied to the delay linestorage to gate each character code into the inputs of the delaychannels so that each character code starts into the inputs of the delaychannels simultaneously with a two-megacycle clock pulse. This gating ofcharacter codes into the inputs of the delay channels by thetwo-megacycle clock pulses takes place whether or not the character codeis being applied to the delay channels from the input register or isbeing recirculated from the ends of the delay channels. In this mannerthe character codes stored in the delay line storage are synchronizedand are maintained in synchronism with the two-megacycle clock pulses.Since the two-megacycle clock pulses are used to gate the charactercodes into the inputs of the delay channels, the character codes can befed into the delay line channels at a rate of one every /2 microsecond.Since the length of the delay channels is 66 microseconds, the capacityof the delay line storage is 132 character codes.

Pulses from the two megacycle clock pulse generator 87 are appliedthrough a gate 93 to an output counter 91. When character codes arebeing read out from the input register 43, the gate 93 will be enabledto allow the clock pulses to be applied to the counter 91. The counter91 is similar to the counter 81 in that it has a capacity of 8 counts,07, it increases its count by one increment in response to each pulsereceived from the clock pulse generator 87, and re-cycles to 0 afterreaching a count of 7. The counter 91 selects the ranks of the inputregister 43 to be read out in accordance with the count registeredthereby and selects the ranks in the input register 43 in response tothe incrementally changing count in the counter 91 in the same sequencethat the counter 81 selects the ranks in the input register. In thismanner, the character codes are read out from the input register in thesame sequence that they are stored and thus are applied to the delayline storage in the same sequence that they are applied on inputchannels 41. The enabling of the gate 93 is controlled by a flip-flop95. When character codes are being read out from the input register, theflip-flop 95 will be in its A state and will apply an enabling signal tothe gate 93. The pulses produced by the two-megacycle clock pulsegenerator 87 are also applied through a gate 97 to a counter 99, whichis referred to as the column counter. The column counter has a capacityof 132, which is the number of characters that can be printed in a lineof print by the printer and which is the capacity of the delay linestorage 45. The enabling of the gate 97 is also controlled by theflip-flop 95. When the flip-flop 95 is in its B state, it will enablethe gate 97 and allow the clock pulses from the clock pulse generator 87to pass through the gate 97 to be counted by the column counter 99.Thus, the flip-flop 95 selects either the counter 91 or the counter 99to count the pulses produced by the clock pulse generator 87. When thecounter 99 reaches a count of 132, the next pulse will re-cycle thecolumn counter 99 and will set a count of l in the column counter 99.Upon reaching a count of 132, the column counter 99 produces an outputpulse on a channel 101. This pulse is applied through a gate 103 to setthe flip-flop 95 in its A state. The gate 103 will be enabled by asignal from the flip-flop 75 through an OR gate 102 whenever theflip-flop 75 is in its A state or in other words when the circuit is inits data insertion phase.

Each time the counter 91 reads a character out from a rank in the inputregister 43, it senses whether the next rank has a clock pulse storedtherein. If the next rank does not have a clock pulse stored therein, itwill mean that all the character codes stored in the input register havebeen read out. clock pulse in the next rank to be read out, the inputregister 43 produces an output pulse on a channel 105 which pulse willset the flip-flop 95 into its B state. Thus in the data insertion phasethe flip-flop 95 will be set into its A state each time the counter 99reaches a count of 132 and the flip-flop 95 will be set to its B statewhen all of the character codes stored in the input register have beenread out. By means of the flip-flop 95, the transferring of thecharacter codes from the input register 43 to the delay line storage 45is carried out so that the character codes are stored in the delay linestorage 45 in their proper order, that is, the same sequence in whichthey are applied to the input channel 41. For example, when the delayline storage 45 has no character codes stored therein and the flip-flop75 has been set into its A state indicating to the information sourcethat the circuit is ready to receive character codes, the charactercodes will be stored in the ranks of the input register 43 in sequence.While these character codes are being stored in the input register 43,the column counter 99 will be counting the clock pulses from thetwo-megacycle clock pulse generator 87. When the column counter 99reaches a count of 132, it will set the flip-flop 95 into its A statethus disabling the gate 97 and enabling the gate 93. Accordingly, thecolumn counter 99 will stop counting and the output counter 91 willstart counting. As a result, the counter 91 will count the clock pulsesfrom the generator 87 and cause the ranks of the input register 43 to beread out in sequence and stored in the delay line storage 45 until allthe character codes in the input register 43 have been read out. At thistime the input register will produce an output pulse on channel 105 andset the flip-flop 95 to its B state. As a result the gate 93 will bedisabled and the gate 97 will be enabled and the column counter 99 willbegin to count again. While the column counter 99 is counting,additional characters will be stored in the input register. The columncounter will count until it again reaches a count of 132 whereupon theflipflop 95 will again be set back into its A state. Since the columncounter 99 will begin counting just after the last character wastransferred from the input register 43 to the delay line storage 45, thecolumn counter 99 will reach a count of 132 just at the time thecharacters that have been stored in the delay line storage 45 have beenre-circulated and are in the same position in the delay line storage 45that they were in when the last character was transferred from the inputregister 43. Accordingly, when the flip-flop 95 switches to its A stateand the counter 91 commences to again count pulses from the clock pulsegenerator 87 causing the newly stored character codes to be read outfrom the input register, the new character codes will be stored in thedelay line 45 right behind the previously stored character codes. Thus,in this manner, the character codes are stored in the delay line storage45 in the same sequence that they were applied to the input channel 41.The process of new character codes being stored in the input registerand then transferred to the delay line storage 45 right behind thepreviously stored characters in the delay line storage will continueuntil 132 characters have been stored in the delay line storage, thusfilling the delay line storage to its capacity.

In response to the finding of no When the delay line storage has beenfilled to its capacity, the flip-flop 75 is switched to its B state thusindicating to the information source that the circuit is no longer readyto accept character codes and preventing the acceptance of charactercodes by removing the enabling signal from the gate 73 and therebypreventing the gates 79 from receiving the strobe pulses. The switchingof the flip-flop 75 to its B state is accomplished by means of a counter107 referred to as the line counter. The pulses produced by thesynchronizer 85 on channel 89 are applied to the line counter 107through an OR gate 109. As was pointed out above, the synchronizer 85produces an output pulse on channel 89 for each clock pulse appliedthereto through the delay line 83. Thus, when the flip-flop 75 is in itsA state and is accepting information from the information source, theline counter 107 will receive one pulse for each character applied tothe channels 41 and passing through the gates 79. Thus the line counter107 will count the characters stored in the input register 43. When 132characters have been stored in the input register 43 after the flip-flop75 has been switched to its A state, the line counter 107 will registera count of- 132. Upon registering a count of 132, the line counter 107resets itself to zero and applies a pulse to a gate 111 which will beenabled by the flip-flop 75 when the flip-flop 75 is in its A state.Accordingly, the

' pulse produced by the line counter 107 Will pass through the gate 111whereupon the pulse will set the flip-flop to its B state, thusdisabling the gate 73 and indicating to the information source that itis no longer accepting character codes. The pulse passing through thegate 111 will also set a flip-flop 113 in its B state. When the flipflop113 is set into its B state, it will apply an enabling signal throughthe OR gate 102 to the gate 103 so that the gate 103 will continue to beenabled after the flip-flop 75 has been switched to its B state. Thisenabling of the gate 103 by the flip-flop 113 is to permit the remainingcharacter codes that are stored in the input register to be read outafter the line counter 107 has reached a count of 132. Thus, when thecolumn counter 99 next reaches a count of 132 after the line counter 107has reached a count of 132 it will switch the flip-flop to its A stateand cause the remaining character codes stored in the input register 43to be transferred to the delay line storage 45. The last character coderead out from the input register 43 at this time will be the l32ndcharacter code applied to the input channels 41 after the flipflop 75was switched to its A state. Thus, the delay line storage 45 will befilled to its capacity with 132 character codes. When the last charactercode is read out from the input register 43 and an output pulse isproduced on channel setting the flip-flop 95 back to its B state, thepulse produced on channel 105 will also set the flip-flop 113 back toits A state. Thus, the gate 103 will be disabled and subsequent pulsesproduced on channel 101 When the column counter 99 reaches a count of132 will not be applied to the flip-flop 95 to set it back to its Astate. When the flip-flop 113 is set back to its A state following thesetting of the flip-flop 75 to its B state, the data insertion phase isended and the print phase begins.

In the print phase when the flip-flop 75 has been set to its B state andthe flip-flop 113 has been set to its B state and back to its A state,no pulses will be applied to the output counter 91 and no charactercodes will be accepted from the information source through the gates 79.The circuit will then be ready to carry out the operation of printingthe charatcer codes that are stored in the delay line storage 45.

When the flip-flop 75 is in its E state, it will apply an enablingsignal to a gate 115, which also receives the count pulses from the tonewheel 49 produced on channel 53. However, in order to be enabled andpass the count pulses on channel 53, the gate 115 must also receive anenabling signal from the flip-flop 113, which will apply an enablingsignal to the gate 115 when it is in its A state. the gate 115 will beenabled to pass count pulses on channel 53 after the flip-flop 75 hasbeen switched to its B state upon the 132nd character being stored inthe input register 43 and after the flip-flop 113 has been switched backto its A state upon the 132nd character being transferred from the inputregister to the delay line storage. Each pulse passing through the gate115 is applied to a multivibrator 117, which in response to each appliedpulse produces a ISO-microsecond output pulse. This 100- microsecondoutput pulse will enable a gate 119 for its duration. The gate 119 isconnected to receive the pulses produced on channel 101 by the columncounter 99. Thus, the gate 119 will receive the pulse firom the columncounter 99 each time the column counter 99 reaches a count of 132. Whenthe vate 119 is enabled, the pulses produced on channel 101 by thecolumn counter 99 will pass through the gate 119 and set a flip-flop 121in its A state. Upon being set in its A state, the flip-flop 21 willenable a gate 122, which is also connected to receive the pulsesproduced on channel 101. Thus, the next pulse produced on channel 101 bythe counter 99 after the one that has set the flip-flop 121 into its Astate will pass through the gate 122 whereupon this pulse will set theflip-flop 121 back to its E state. Accordingly, the flipflop 121 will bein its A state for the period between the first two pulses produced onchannel 101 after a pulse passes through the gate 115. In other words,the flipflop 121 will be set into its A state for the period between thenext two pulses produced on channel 101 by the column counter 99 aftereach count pulse is produced on channel 53 by the tone wheel 49. In thismanner the flip-flop 121 is set into its A state for a 66-microsecondtime interval each time the tone wheel produces a count pulse on channel53. Each 66-microsecond time interval will start when the count in thecolmun counter 99 first reaches 132 after a count pulse is produced onchannel 53 and will end when the column counter next reaches a count of132.

As was pointed out above the count in the column counter 99 is held at132 as new character codes are transferred from the input register tothe delay line storage in the data insertion phase and then startscounting again with l on the next pulse produced by the two-microsecondclock pulse generator 87 after the last character code is transferred tothe delay line storage. Thus, after the delay line storage has beenfilled with 132 character codes, the column counter will start with acount of one simultaneously with the time that the first character codethat was stored in the-delay line storage recirculates from the ends ofthe delay channels to the inputs of the delay channels in the delay linestorage. Accordingly, as each character code recirculates in the delayline storage from the ends of the delay channels to the inputs of thedelay channels, the count registered by the counter 99 will correspondto the order in which such character code was transferred to the delayline storage and to the column position in which the characterrepresented by such character code is to be printed.

As the character codes in the delay line storage 45 recirculate, theyare compared with the counts registered by the counter 47, which aspointed out above registers a count corresponding to the character codeof the line of characters on the drum about to come into the printposition. Whenever a character code in the delay line storage equalingthe code of the count registered in the counter 47 recirculates from theends of the delay channels to the inputs of the delay channels, theidentity of the two codes will be detected by the comparison circuit 57which will then produce a hit pulse on a channel 123. Thus, a pulse willbe produced on channel 123 each time a character code in the delay linestorage identical to the code of the count registered in the counter 47recirculates Thus,

from the ends of the delay channels to the inputs of the delay channels.The pulses produced on channel 123 are applied to a gate 125, which willbe enabled whenever the flip-flop 121 is in its'A state. When the gateis enabled the hit pulses will pass through to the selector matrix 61.Thus, after a count pulse is produced on channel 53, the gate 125 willpass any hit pulses produced on channel 123 during the 66-microsecondinterval starting at the time the counter 99 first reaches a count of132 after the pulse produced on channel 53 and ending the next timethecounter 99 reaches a count of 132. Thus the gate 125 will be enabledto pass hit pulses to the selector matrix 61 for one-completerecirculation of all 132 character codes stored in the delay linestorage.

The selector matrix 61 selects stages in the hit register 59corresponding to the count registered by the counter 99 and stores thehit pulses in the stages selected thereby. The hit register 59 has 132stages, one corresponding to each column of characters to be printed bythe apparatus. If the columns are considered numbered 1 to 132 startingfrom the left-hand side of the paper, then the count registered by thecounter 99 will equal the number of the column in which there is to beprinted the character represented by the character code that ispresently recirculating from the ends of the delay channels to theinputs of the delay channels in the delay line storage. Thus, when a hitpulse is produced on channel 123, the count registered by the columncounter 99 will equal the number of the column in which there is to beprinted the character represented by the character code which caused thehit pulse to be produced. The selector matrix 61 under the control ofthe count registered by the counter 99 stores each hit pulse appliedthereto in the stage of the hit register 59 corresponding to the countrepresented in the counter 99 and thus corresponding to the column inwhich there is to be printed the character represented by the charactercode that caused the hit pulse. In this manner pulses are stored in thestages of the hit register 59 corresponding to the columns in whichthere is to be printed the character represented by the code of thecount registered in the counter 47. The next pulse produced on thechannel 53 will increase the count registered by the counter 47incrementally by one and will also enable a .set of 132 gates 63 readingout the pulses stored in the hit register 59. When each count pulse isproduced on channel 53, a row of characters will be in the printposition. The code representing this row of characters will be the codeof the count registered in the counter 47 just prior to the time thecount pulse was produced. Each of the 132 output channels from the gates63 is connected to the input of a difierent one of the hammer drivingpulse generators 64, each of which is connected to apply a driving pulseto the solenoid of a dilTerent one of the print hammers. Each of thehammer driving pulse generators 64 is connected to receive a pulse froma different one of the stages of the hit register 59 when the gates 63are enabled and the hammer solenoid which is connected to be energizedby each hammer driving pulse generator is located opposite the column onthe paper 33 corresponding to the stage of the hit register to whichsuch hammer driving pulse generator is connected. The hammer solenoidsupon receiving the hammer driving pulses Will strike the paper and theink impregnated ribbon against the print drum and print the characterswhich are under the hammers at this time. The tone wheel 49 ispositioned relative to the print drum so that the characters printed inthis manner will correspond to the code of the count that was registeredin the counter 47 just prior to the last count pulse which enabled thegates 63 and caused the energization of the appropriate solenoids. Thusthe character represented by the code of the count registered in thecounter will be printed in the columns on the paper corresponding to theorder in which the character codes representing such character arestored in the delay of his pulses.

As each count pulse is produced on channel 53, the count in the counter47 increases incrementally and as each new count is registered in thecounter 47 it is compared with the entire contents of the delay linestorage in the manner described above and hit pulses are stored in thestages of the hit register corresponding to the columns in which thereis to be printed the character represented by the code of such newcount. This process is continued until all of the characters stored inthe delay line storage have been printed, each in the columncorresponding to its position in the delay line storage.

Each count pulse produced on channel 53 and passing through the enabledgate 115 is also applied to the line counter 167 through the OR gate109. Accordingly, the counter 107 will count the pulses passing throughthe gate 115. When the counter 107 reaches the count of 53, that is,about 4 /2 milliseconds before the drum has completed one revolutionfollowing the initiation of the print phase, the counter 197 willproduce an output pulse on a channel 131. The pulse produced on channel131 is referred to as the anticipated end-of-print pulse. This pulse isapplied to a gate 133 which will be enabled by a signal from theflip-flop 75 when the flip-flop 75 is in its B state as .it will beduring the print phase. Thus, the anticipated end-of-print pulse willpass through the enabled gate 133 whereupon it will be delayed by adelay line 135 sufficiently long for the drum to complete its revolutionand for all of the characters on the drum to be printed. When the pulsehas passed through the delay line 135, all of the columns in whichcharacters are to be printed on the paper will be printed. The pulseafter passing through the delay line 135 resets the counter 107 to zeroand sets the flip-flop 75 back in its A state. The flip-flop '75 thensends a signal to the information source indicating that it is ready toaccept more character codes and en abling the gate 73 so that morecharacter codes may he applied to the input register 43. The pulsepassing through the delay line 135 is also applied to a multivibrator137 which applies a pulse to the delay line storage to inhibitrecirculation in the delay lines for a period long enough to clear thedelay line storage of all the characters stored therein. The pulsepassing through the delay line 135 is also applied to the paper advancecontrol circuitry and initiates an advance of the paper bringing thenext line of the paper under the hammers to be printed. The process thenrepeats itself to print another line of characters selected inaccordance with the character codes fed on input channels 41. In thismanner any of the alpha-numeric characters or any of the special curveplotting characters may be printed in any line of the paper coming underthe print hammers.

When the apparatus is to be operated in the alphanumeric rnode, a signalwill be applied to an input channel 139 to set a flip-flop 141 in its Astate. When the apparatus is to be operated in its plot mode, an inputsignal is applied on an input channel 143 to set the flip-flop 141 inits B state. To advance the paper one increment the pulse passingthrough the delay line 135 sets a flipilop 145 in its A state. When theflip-flop 145 is in its A state, it will apply an enabling signal to agate 147 and a gate 149. When the flip-flop 141 is in its A state itwill apply an enabling signal to the gate 147 and when the flip-flop 141is in its B state, it will apply an enabling signal to the gate 149.When the gate 147 receives enabling signals from both the flip-flops 141and 145, it will apply a signal to a clutch-driving circuit 151 which inresponse to receiving the signal will energize a clutch 153 and causethe clutch 153 to engage. Thus, the clutch 153 will be engaged inresponse to the pulse passing through the delay line 135 if theflip-flop 141 has been set into its A state 12 in response to a signalon input channel 139 calling for the circuit to operate in thealpha-numeric mode. cordingly, the clutch 153 is referred to as thealphanumeric clutch. When the gate 149 receives enabling signals fromthe flip-flop 141 and the flip-flop 145, it will apply agsignal to aclutch-driving circuit 155, which in response to the signal from thegate 149 will energize a clutch 157 and cause the clutch 157 to engage.Thus, the clutch 157 will be engaged when the flip-flop 141 is in .its Estate and the flip-flop 145 is in its A state. Accordingly, the clutch157 Will be engaged in response to a paper advance pulse from the delayline when the circuit has been placed in the plot mode by a signalapplied on input channel 143. Accordingly, the clutch 157 is referred toas the plot clutch.

The clutches 153 and 157 are schematically illustrated in FIG. 1. Asshown in FIG. 1 the outputs of both of the clutches 153 and 157 drivethe paper drive mechanism 34 for the paper 33. A motor 159 drives theinput side of the clutch 153 at one speed and drives the input side ofthe clutch 157 at a lower speed. The input side of the clutch 153 isdriven at a speed such that when it is engaged, it will cause the paper33 to be advanced at a rate of 25 inches per second. The input side ofthe clutch 157 is driven by the motor 159 at a speed such that when itis engaged, it will cause the paper 33 to advance at a rate of 9 inchesper second. Thus, when a paper advance pulse is applied to the flip-flopset-ting the flip-flop 145 in its A state and the circuit is operatingin the alpha numeric mode, it will cause the clutch 153 to engage andstart the paper to advance at a rate of 25 inches per second. If thecircuit is operating in the plot mode, then in response to a paperadvance pulse applied to the flipflop 145, the clutch 157 will engageand cause the paper to start advancing at a rate of 9 inches per second.

Along with the paper drive mechanism the clutches 153 and are connectedto drive tone wheels 161 and 163, which accordingly rotate at a ratecorresponding to the rate that the paper 33 is advanced. The tone wheels161 and 163 are like the tone wheel 49 in that they compriselow-reluctance material with radial slots distributed around theirperipheries. The tone wheels 161 and 163 cooperate with transducers 165and 167, respectively. Each time a slot in the tone wheel 161 passesunder the transducer 165, the transducer 165 will produce an outputpulse and each time a slot on the tone wheel 163 passes under thetransducer 167, the transducer 167 will produce an output pulse. Theslots on the tone wheel 161 are spaced so that the transducer 165 willproduce an output pulse for every of an inch that the paper 33 advances.The slots in the tone wheel 163 are spaced so that the transducer 167will produce an output pulse for every of an inch that the paper 33advances.

As shown in FIG. 12 the output pulses produced by the tone wheel 161 areapplied to one contact of a relay 169 and the output pulses produced bythe tone wheel 163 are applied to another contact of the relay 169. Whenthe relay 169 is not energized, it will apply the pulses produced by thetone wheel 161 toa channel 171 and when the relay 169 is energized, itwill connect the output pulses produced by the tone wheel 163 to thechannel 171. The relay 169 will be energized whenever the flip-flop 141is in its B state and will not be energized whenever the Hip flop 141 isin its A state. Thus, the output pulses produced by the tone wheel 161will be applied to the channel 171 when the circuit is operating in thealpha-numeric mode and the output pulses of the tone wheel 163 will beapplied to the channel 171 when the circuit is operating in the plotmode. Accordingly, the tone wheel 161 is referred to as thealpha-numeric tone wheel and the tone wheel 163 is referred to as theplot tone wheel. Each time a pulse is applied to channel 171 from eitherthe tone wheel 161 or the tone wheel 163, it will set the flip-flop 145to its B state and accordingly the flip-flop 145 will no longer apply anenabling signal to the gates 147 and 149.

If the circuit is operating the alpha-numeric mode so that the clutch153 is engaged, then when the enabling signal from the flip-flop 145 isno longer applied to the gate 147, the clutch driving circuit 151 willno longer receive a signal from the gate 147 and accordingly willde-energize the clutch 153, which upon being de-energized willdisengage. If the circuit were operating in the plot mode, then when apulse from the tone wheel 163 sets the flipflop 145 in its B state sothat the gate 149 no longer receives an enabling signal, theclutch-driving circuit 155 will no longer receive a signal from the gate149 and in response to the termination of this signal will de-energizethe plot mode clutch 157, whereupon the plot mode clutch 157 willdisengage.

The flip-flop upon switching to its B state will apply an actuatingsignal to a brake-energizing circuit 173, which in response to receivingthe actuating signal will energize a brake 175. The brake 175 as shownin FIG. 1 operates on the paper drive mechanism 34 and upon beingenergized will stop the paper drive mechanism and thus halt the advanceof the paper 33.

Accordingly, if the circuit is operating in the alphanumeric mode sothat pulses from the alpha-numeric tone wheel 161 are applied on channel171 and so that the clutch 153 will be engaged in response to paper feedpulses applied to the flip-flop 145 from the delay line 135, thefollowing action will occur in response to a paper feed pulse. First,the clutch 153 will engage thus causing the paper 33 to start advancingat a rate of 25 inches per second. When the paper has advanced to apoint where the tone wheel 161 produces an output pulse, this pulse Willcause the clutch 153 to disengage and the brake 175 to engage stoppingthe paper advance. Since the alpha-numeric tone Wheel 161 produces anoutput pulse for every f an inch that the paper 33- advances, the paperwill have advanced of an inch when it is stopped by the brake 175 and itwill advance in increments of of an inch for each paper advance pulseapplied from the delay line 135 to the flip-flop 145.

When the circuit is operating in the plot mode, each paper advance pulseapplied to the flip-flop 145 will cause the plot mode clutch 157 toengage and cause the paper 33 to start advancing at a rate of 9 inchesper second. When the paper has advanced to a point where the plot toneWheel 163 produces an output pulse, this output pulse will switch theflip-flop 145 to its B state and cause the plot mode clutch to disengageand the brake 175 to be energized. Because the plot tone wheel producesoutput pulses at the rate of one output pulse per of an inch of paperadvance, the paper will have advanced of an inch when it is stopped bythe brake 175. In this manner, each paper advance pulse applied to theflip-flop 145 Will cause a paper advance of of an inch when the circuitis operating in the plot mode. In this manner the paper can be advancedin increments of of an inch or of an inch. When curves or graphs arebeing plotted the increments of of an inch provide good resolution inthe vertical direction.

Each paper advance pulse passing through the delay line 135 is alsoapplied to a ribbon advance apparatus 177 which advances the ribbon oneincrement in response to each received pulse in the conventional mannerso that the ribbon is advanced each time the paper is advanced.

FIG. 13 illustrates the details of the input register in block form. InFIG. 13 the eight ranks of the input register are designated by thereference number 179. Each of the ranks 179 comprises six flip-flops sothat the rank is capable of storing a six-bit binary code. The six-bitbinary character codes passing through the gates 79 are applied into theinput register on six input channels 181. A set of six gates 183 isassociated with each of the ranks 179 and the six input channels areapplied to each set of gates 183. The gates 183 are enabled in sequenceby output signals produced by the counter 81 on channels 185 insequence. The counter 81 conveniently may be a flip-flop ring counter toproduce the output signals on the channels in sequence. Thus eachcharacter code applied on input channels 181 will pass through adifferent set of gates 183 depending upon the count registered by thecounter 81. Upon passing through a set of gates 183, the character codeis stored in the six flip-flop stages of one of the ranks 179.Associated with each rank 179 is an additional fiip-fiop 187 for storingthe clock pulse. The clock pulses applied to the register on inputchannel 89 are applied to the flip-flops 187 through gates 189, therebeing one gate 189 associated with each flip-flop 187 and rank 179. Whenthe counter 81 produces a signal on one of its output channels 185 toenable one set of gates 183 associated with one of the ranks 179, itwill also enable the gate 189 associated with this rank 179 so that theclock pulse applied on channel 89 will be stored in the flip-flop 187along with the character code stored in the rank 179. Each time thecounter 81 produces a signal on an output channel 185 to enable a set ofgates 183 associated with a rank 179, this signal will also be appliedto the next succeeding rank 179 to set this rank to zero so that it willbe ready to receive the next character code when it is applied on inputchannels 181. In this manner the character codes are stored in sequencein the ranks 179 and a clock pulse is stored in a flip-flop 187 alongwith each character code stored. When the counter 91 reads out thecharacter codes from the input register, it produces enabling signals onoutput channels 191 in sequence. The counter 91 conveniently may be aflip-flop ring counter to produce the output signals on channels 191 insequence. Each rank 179 has a set of output gates 193 associatedtherewith. These sets of output gates 193 are enabled in sequence by theoutput signals produced by the counter 91 on the channels 191. When oneof the sets of gates 193 is enabled, it will read out the character codestored in the rank 179 with which it is associated and send thecharacter code to the delay line storage. In this manner the charactercodes are read out of the ranks 179 in sequence. Each time a signal isproduced on one of the channels 191 by the counter 91, it will set theclock pulse flip-flop 187 associated with the same rank back to zero andit will also enable a gate 195 associated with the next succeeding rankand the clock pulse flip-flop 187 associated with this rank. Each gate195 is connected to read out the clock pulse flipflop that it isassociated with when the gate 195 is enabled. Thus, while the counter 91is reading out one of the ranks 179, it is also reading out thecondition of the clock pulse flip-flop 187 associated with the nextsucceeding rank. The clock pulse flip-flops 187 are connected to thegates 195 so that they will produce output signals only if they do notstore a clock pulse. Thus, the gate 195 associated with the nextsucceeding rank will produce an output signal when the preceding rank isread out if the clock pulse flip-flop 187 associated with the nextsucceeding rank does not store a clock pulse. The outputs of the gates195 are all applied through an OR gate 197 to the output channel 105. Inthis manner an output pulse is produced on channel 105 when no charactercode is stored in the next succeeding rank when the preceding rank isread out.

FIG. 14 illustrates details of the synchronizer 85. As shown in FIG. 14the character code clock pulses from delay line 83 are applied to aflip-flop 199 to set the flipflop 199 in its A state. The two-megacycleclock pulses from the clock pulse generator are applied to a flip-flop201 to cause the flip-flop 201 to switch from whatever state it is in tothe opposite state. Accordingly, the fiip-fiop 201 produces outputpulses on a channel 203 at a frequency of one megacycle. These pulsesare applied through a delay line 205 which delays the pulses by A of amicrosecond so that the output pulses coming out of the delay line 205will be between the two-megacycle clock pulses produced by the clockpulse generator. The flip-flop 199 upon being set into its A stateapplies a signal to a flip-flop 207.to set the flip-flop 207 in its Astate. The pulses passing through the delay line 205 out of phase withthe two-megacycle clock pulses are applied to the flip-flop 207 to setthe flip-flop 207 in its B state. Thus, the flip-flop 207 will be set inits B state at a time between the two-megacycle clock pulses. Upon beingset in its B state the flip-flop 207 produces an out put pulse onchannel 89. In this manner the synchronizer produces output pulses onchannel .89 between the tWo-megacycle clock pulses. When the flip-flop207 is set into its A state by the signal from the flip-flop 199 it willenable a gate 209. The pulses produced on channel 203 by the flip-flop201 are also applied to the gate 209 and when the gate 209 is enabled,they will pass through the gate 209 to set the flip-flop 199 back to itsB state. In this manner the flip-flop 199 is made ready to receive thenext character clock pulse from the delay line 83.

FIG. 15 is a block diagram of one delay channel in the delay linestorage 45 and illustrates how the bits are transferred into the delaychannel and recirculated in the delay channel. As shown in FIG. 15 eachbit of a character code from the input register is applied through an ORgate 211 to a pulse shaper 213, which shapes the pulse from the inputregister and applies it to a gate 215. The gate 215 also receives thetwo-megcycle clock pulses from the clock pulse generator and thus willpass the bits represented by the pulses from the pulse shaper 213simultaneously with pulses produced by the clock pulse generator. Thepulse shaper 213 produces an output pulse of sufiicient length so that atwo-megacycle clock pulse will occur while the pulse representing thecharacter bit is being produced by the pulse shaper 213. The characterbit pulses on passing through the gate 215 are applied to the input of a66-microsecond delay line 217. Upon passing through the 66-microseconddelay line 217, the character bit pulses are applied to a normallyenabled gate 219, which can be disabled by a pulse from themultivibrator 137 to clear the delay line storage. After passing throughthe gate 219 the character bit pulses are amplified by an amplifier 221and then applied back through the OR gate 211 to the input of the pulseshaper 213. In this manner the character bits are continuouslyrecirculated. In the delay line storage binary ones are represented bypulses and binary zeros are represented by the absence of pulses so acharacter bit pulse represents a binary one. Each of the six characterstages comprising the six delay channels of the delay line storage isidentical to the stage shown in FIG. 15.

FIG. 16 illustrates the details of the comparison circuit 57. As shownin FIG. 16 the six bit binary character codes recirculating in the delayline storage 45 are applied to input channels 223 of the comparisoncircuit as they recirculate. Each of the input channels 223 is appliedto a different bit comparison unit 225. Each of the bit comparison unitsis connected to receive a signal from a different stage of the binarycounter 47. Each bit comparison unit 225 compares the binary signalsrecirculating in the delay channel to which it is connected with thesignal stored in the stage of the binary counter to which it isconnected. Each time it detects that the two binary sig- :nals are thesame, the bit comparison unit will produce an output pulse. Each of theoutputs of the bit comparison units 225 are connected to a differentinput of a six-way AND gate 227. This six-way AND gate will produce anoutput pulse on channel 123 when it receives pulses on all :six inputssimultaneously from the bit comparison units 225. This simultaneousapplication of pulses to the gate 227 will only occur when a charactercode is recirculated from the ends of the delay channels identical tothe code of the count registered in the counter 47.

FIG. 17 illustrates the details of a bit comparison unit 225. As shownin FIG. 17 the signal on one of the channels 223 is applied to a gate229 and the signal from one stage of the binary counter 47 is applied tothe gate 229 on a channel 230. Thus, when a bit pulse representing abinary one is applied to the channel 223 shown in FIG. 17 and a binaryone is registered in the stage of the binary counter 47 connected to thechannel 230, the gate 229 will pass the bit pulse on channel 223. Theinput channel 223 is also connected to an inverter 231, which applies anenabling signal to a gate 223 whenever it does not receive a bit pulseon channel 223. The channel 230 is also connected to an inverter 235,which will apply an enabling signal to the gate 233 whenever the stageof the binary counter 47 to which the channel 230 is connected registersa Zero. The clock pulses from the two-megacycle clock pulse generatorare also applied to the gate 233. If the gate 233 receives enablingsignals from both the inverters 231 to 235, it will pass a two-megacycleclock pulse from the clock pulse generator. Thus, the gate 233 willproduce an output pulse if a signal representing a binary zero isrecirculated in the delay channel connected to the channel 223 shown inFIG. 17, and a binary zero is stored in the stage of the binary counterconnected to channel 230. The output of the gate 229 and the output ofthe gate 233 are connected through an OR gate 237 to the output of thebit comparison unit. Accordingly the gate 237 will produce an outputpulse whenever the binary signal recirculating in the delay channelconnected to the channel 223 in FIG. 17 is the same as the binary signalstored in the stage of the binary counter 47 connected to the channel230.

FIG. 18 illustrates the details of the selector matrix and how itselects a different stage in the hit register for 'each of the 132counts that can be registered in the counter 99, which is an 8-stagebinary counter. As shown in FIG. 18 two conductors 239 and 241 areconnected to each stage of the binary counter 99 so that the conductor239 will have a high potential applied to it when the stage registers abinary one and the conductor 241 will have a high potential applied toit when the stage registers a binary zero. These conductors 239 and 241are connected in different combinations to 132 output conductors 243.The conductors 239 and 241 are connected to the output conductors 243 bymeans of diodes, which are represented by circles at the intersectionsof the conductors 243 with the conductors 239 and 241 and which aredesignated by the reference number 245. Each of the conductors 243 isconnected to at least one of the conductors 239 and 241 connected toeach stage of the binary counter 49 so that each conductor 243 isconnected to a combination of eight conductors 239 and 241. Moreover,each of the 132 conductors 243 is connected to a different combinationof the conductors 239 and 241. Each of the conductors 243 is connectedthrough a resistor 247 to a source of potential applied at a terminal249. With this arrangement only one of the conductors 243 will have ahigh potential applied thereto and the particular one of the conductors243 that will have the high potential applied thereto will depend uponthe count registered in the counter 99. A different conductor 243 willhave a high potential applied thereto for each different count that canbe registered in the counter 99. The conductors 243 are each connectedto the input of a different gate 251, each of which is connected toreceive the hit pulses from the gate 125. The one of the gates 251 whichreceives a high potential applied thereto will be enabled and pass thepulse. The outputs of each of the gates 251 are connected to a differentstage of the hit register 59. In this manner the hit pulses are storedin the stages of the hit register 59 corresponding to the countregistered in the counter 99. From the above description it will beapparent that the apparatus of the present invention can plot curves andgraphs at a very high speed with good resolution. The good resolution isobtained because of the character configuration of the specialcharacters and because the paper can be advanced at small increments inthe plot mode. The incremental advance of the paper in the plot mode canalso be used in place of column spacing between 1 7 groups of letters ornumber. For example, suppose it is desired to print a plurality ofseparate groups of numbers providing some information about a particularpoint on a curve. By advancing the tape by of an inch before each groupof characters or numbers are printed, the column spacing between thegroups can be eliminated because the groups will be clearlydistinguishable from each other due to the fact that the individualgroups will be offset from each other by increments of of an inch. Inthis manner, more information may be printed opposite a particular pointon a graph or curve that is being plotted.

The above-described apparatus and the special characters disclosedtherein is a preferred embodiment of the invention. Instead of usingthese particular dot configurations as the special characters forprinting graphs, other configurations can be used. For example, insteadof using the paper feed to obtain the desired resolution in the verticaldirection, additional special characters could be provided with the dotspositioned in the character fields to provide resolution in the verticaldirection. For example, in one special character a dot could be locatedin the upper left-hand corner of the character field, in another specialcharacter the dot could be located in the upper right-hand corner of thecharacter field, in a third special character the dot could be locatedin the middle of the upper side of the character field, etc. Theseparticular special characters subdivide the character field in thevertical direction in the same manner the special characters of thepreferred embodiment described above subdivide the character field inthe horizontal direction. These and many other modifications may be madeto the above described preferred embodiment without departing from thespirit and scope of the invention, which is defined in the appendedclaims.

What is claimed is: 1. A curve plotting apparatus comprising: meansdefining a plurality of characters, each of said characters having acharacter field in which a character mark adapted to be printed ispositioned, each of said character fields being of the same size andshape, the character mark of each of said characters having the sameshape but being located in a difierent position in its character field,means to select one of said characters, and means to print the charactermark of the selected character in a predetermined area on a medium, saidpredetermined area having the same size and shape as said characterfields and the character mark of said selected character being printedin the same position in said predetermined area that the character markis positioned in the field of the selected character. 2. A curveplotting apparatus as recited in claim 1 wherein said character marksare in the form of dots.

3. A curve plotting apparatus as recited in claim 1 wherein said meansfor defining a plurality of characters defines at least one additionalcharacter to be selected by said selecting means, said additionalcharacter having a character field in which two character marks arepositioned, the character field of said additional character having thesame size and shape as the character fields of said plurality ofcharacters, the two character marks of said additional character eachhaving the same shape as the character marks of said plurality ofcharacters and being located in the same position in the character fieldof said additional character as two of the character marks of saidplurality of characters are located.

4. A curve plotting apparatus comprising: means defining a plurality ofcharacters, each of said characters having a character field in which acharacter mark adapted to be printed is positioned, each of saidcharacter fields being of the same size and shape, the character mark ofeach of said characters having the same shape but being located in adifferent position in its character field,

18 means to select one of said characters for each of a plurality ofadjacent predetermined areas on a medium, said predetermined areashaving the same size and shape as said character fields, and means toprint in each of said predetermined areas on said medium the charactermark of the character selected for such area, the character mark printedin each selected predetermined area being located in such predeterminedarea in the same position that the character mark is located in thefield of the character selected for such predetermined area. 5. A curveplotting apparatus comprising: means defining a plurality of rows ofcharacters, each of said characters having a character field in which acharacter mark adapted to be printed is positioned, each of saidcharacter fields being of the same size and shape, said character marksof characters in different rows being in difierent positions in theirrespective character fields and occupying only a small portion of suchfields, means to sequentially move said rows of characters past a printstation, means to advance a web on which printing can be carried outincrementally past said print station, and means to print selectedcharacters in the row of characters at said print station on areas ofsaid Web at said print station opposite the selected characters. 6. Acurve plotting apparatus as recited in claim 5 wherein said meansdefining a plurality of rows of characters is a drum defining saidcharacters on the periphery of said drum and said means to move saidcharacters sequentially past a print station comprises means to rotatesaid drum.

7. A curve plotting apparatus as recited in claim 5 wherein saidcharacter marks are dots.

8. A curve plotting apparatus as recited in claim 5 wherein saidcharacter marks have the same shape.

9. A curve plotting apparatus comprising: means defining a plurality ofrows of characters, each of said characters having a character field inwhich a character mark adapted to be printed is positioned, each of saidcharacter fields being of the same size and shape, said character marksin characters of different rows being in different positions in theirrespective character fields and occupying only a small portion of suchfields, means to sequentially move said rows of characters past a printstation, means to advance a Web on which printing can be carried outincrementally past said print station in increments equal to a fractionof the length of said character fields, and means to print selectedcharacters in the row of characters at said print station on areas ofsaid web at said print station opposite the selected characters. 10. Acurve plotting apparatus comprising: means defining a plurality of rowsof characters, each of said characters having a character field in whicha character mark adapted to be printed is positioned, each of saidcharacter fields being of the same size and shape, the character marksin a first one of said rows of said characters being positioned in themiddle of their respective character fields and occupying a smallportion of such character fields, the character marks of the charactersof a second one of said rows being positioned in the middle of theleft-hand side of their respective character fields and occupying asmall portion of such fields, the character marks of the characters in athird one of said rows being positioned in the middle of the right-handside of their respective character fields and occupying only a smallportion of such fields, means to sequentially move said rows ofcharacters past a print station,

19 means to advance a web on which printing can be carried outincrementally past said print station, and means to print selectedcharacters in the row of characters at said print station on areas ofsaid web at said print station opposite the selected characters. 11. Acurve plotting apparatus comprising: means defining a plurality of rowsof characters, each of said characters having a character field in whicha character mark adapted to be printed is positioned, each of saidcharacter fields being of the same size and shape, the character marksin the characters of a first plurality of different ones of said rowsbeing in different positions in their respective character fields andoccupying only a small portion of such fields, the characters of asecond plurality of said rows being alpha-numeric characters,

means to sequentially move said rows of characters past a print station,means to advance a web on which printing can be carried outincrementally past said print station, and means to print selectedcharacters in a row of characters at said print station on areas of saidweb at said print station opposite the selected characters.

12. A curve plotting apparatus comprising:

means defining a plurality of alpha-numeric characters,

and a plurality of special characters, each of said characters having acharacter field in which a character mark adapted to be printed ispositioned, each of said character fields being of the same size andshape, the character mark of each of said special characters having thesame shape but being located in a different position in its characterfield,

means to select one of said characters, and

means to print the character mark of the selected character in apredetermined area on a medium, said predetermined area having the samesize and shape as said character fields and the character markof saidselected character being printed in the same position in saidpredetermined area that the character mark is positioned in the field ofthe selected character.

13. A curve plotting apparatus as recited in claim 12 wherein thecharacter marks of said special characters are in the form of dots.

14. A curve plotting apparatus as recited in claim 12 wherein said means.for defining a plurality of characters defines at least one additionalspecial character to be selected by said selecting means, said additionspecial character having a character field in which two character marksare positioned, the character field of said additional special characterhaving the same size and shape as the character fields of said pluralityof special characters and said plurality of alpha-numeric characters,the two character marks of said additional special character each havingthe same shape as the character marks of said plurlity of specialcharacters and being located in the same position in the character fieldof said additional character as two of the character marks of saidplurality of special characters are located.

15. A curve plotting apparatus comprising:

means defining a plurality of alpha-numeric characters and a pluralityof special characters each of said characters having a character fieldin which a character mark adapted to be printed is positioned, each ofsaid character fields being of the same size and shape, the charactermark of each of said special characters having the same shape but beinglocated in a different position in its character field,

means operable to select one of said characters for each of a pluralityof adjacent predetermined areas on a medium, said predetermined areashaving the same size and shape as said character fields, and

means to print in each of said predetermined areas on said medium thecharacter mark of the character selected for such area, the charactermark printed in 20' each selected predetermined area being located insuch predetermined area in the same position that the character mark islocated in the field of the character selected for such predeterminedarea.

16. A curve plotting apparatus comprising:

means defining a plurality of rows of alpha-numeric characters andspecial characters, each of said characters having a character field inwhich a character mark adapted to be printed is positioned, each of saidcharacter fields being of the same size and shape, said character marksof said special characters in different rows being in differentpositions in their respective character fields and occupying only asmall portion of such fields,

means to sequentially move said rows of characters past a print station,means to advance a web on which printing can be carried outincrementally past said print station, and means to print selectedcharacters in the row of characters at said print station on areas ofsaid web at said print station opposite the selected characters. 17. Acurve plotting apparatus as recited in claim 16 wherein said meansdefining a plurality of rows of char-acters is a drum defining saidcharacters on the periphery of said drum and said means to move saidcharacters sequentially past a print station comprises means to rotatesaid drum.

18. A curve plotting apparatus as recited in claim 16 wherein thecharacter marks of said special characters are dots.

19. A curve plotting apparatus as recited in claim 16 wherein thecharacter marks of said special characters have the same shape.

20. A curve plotting apparatus comprising: means defining a plurality ofrows of alpha-numeric characters and special characters, each of saidcharacters having a character field in which a character mark adapted tobe printed is positioned, each of said character fields being of thesame size and shape, said character marks in said special characters ofdifferent rows being in difierent positions in their respectivecharacter fields and occupying only a small portion of such fields,means to sequentially move said rows of characters past a print station,

means to advance a web on which printing can be carried outincrementally past said print station in increments equal to a fractionof the length of said character fields, and

means to print selected characters in the row of characters at saidprint station on areas of said Web at said print station opposite theselected characters. 21. A curve plotting apparatus comprising: meansdefining a plurality of rows of alpha-numeric characters and a pluralityof rows of special characters, each of said characters having acharacter field in which a character mark adapted to be printed ispositioned, each of said character fields being of the same size andshape, the character marks in a first one of said rows of said specialcharacters being positioned in the middle of their respective characterfields and occupying a small portion of such character fields, thecharacter marks of the characters of a second one of said rows of saidspecial characters being positioned in the middle of the left-hand sideof their respective character fields and occupying a small portion ofsuch fields, the character marks of the characters in a third one ofsaid rows of said special characters being positioned in the middle ofthe right-hand side of their respective character fields and occupyingonly a small portion of such fields,

means to sequentially move said rows of characters past a print station,

means to advance a web on which printing can be carried outincrementally past said print station, and

meansto print selected characters in the row of characters at said printstation on areas of said web at said print station opposite the selectedcharacters.

22. A curve plotting apparatus comprising:

means defining a plurality of characters, each of said characters havinga character field in which a character mark adapted to be printed ispositioned, each of said character fields being of the same size andshape, a first of said characters consisting of a single character mark,a second of said characters consisting of a single character mark of thesame size and shape as the character mark of said first character andlocated in a position in its character field different from the positionof the character mark in the character field of said first character, athird of said characters comprising two character marks each of the samesize and shape as the character marks of said first and secondcharacters and located in the same positions in the character field ofsaid third character as the character marks of said first and secondcharacters are positioned in the character fields of said first andsecond characters,

means to select one of said characters, and

means to print the character mark configuration of the selectedcharacter in a predetermined area on a medium, said predetermined areahaving the same size and shape as said character fields, and thecharacter mark configuration of the selected character being printed inthe same position in said predetermined area that the character markconfiguration is positioned in the field of the selected character.

23. A curve plot-ting apparatus comprising:

means defining a plurality of characters, each of said characters havinga character field in which a character mark adapted to be printed ispositioned, each of said character fields being of the same size andshape, a first of said characters consisting of a single character markoccupying a small portion of its character field, a second of saidcharacters consisting of a single character mark occupying a smallportion of its character field and located in a position in itscharacter field different from the position of the character mark in thecharacter field of said first character, a third of said characterscomprising two character marks each occupying a small portion of thecharacter field of said third character and located in the samepositions in the character field of said third character as thepositions of the character marks of said first and second characters inthe character fields of said first and second characters,

means to select one of said characters, and

means to print the character mark configuration of the selectedcharacter in a predetermined area on a medium, said predetermined areahaving the same size and shape as said character fields, and thecharacter mark configuration of the selected character being printed inthe same position in said predetermined area that the character markconfiguration is positioned in the field of the selected character.

24. A curve plotting apparatus comprising:

means defining a plurality of said characters, each of said charactershaving a character field in which a character mark adapted to be printedis positioned, each of said character fields being of the same size andshape, a first of said characters consisting of a single character markand occupying a small portion of its character field, a second of saidcharacters consisting of a single character mark of the same size andshape as the character mark of said first character and located in aposition in its character field different from the position of thecharacter mark in the character field of said first character, a thirdof said characters comprising two character marks each the same size andshape as the character mark of said first character and located in thesame positions 22 in the character field of said third character as thepositions of the character marks of said first and second characters inthe character fields of said first and second characters,

means to select one of said characters, and

means to print the character mark configuration of the selectedcharacter in a predetermined area on a medium, said predetermined areahaving the same size and shape as said character fields, and thecharacter mark configuration of the selected character being printed inthe same position in said predetermined area that the character markconfiguration is positioned in the field of the selected character.

25. A curve plotting apparatus comprising:

means defining a plurality of rows of characters, each of saidcharacters having a character field in which a character mark adapted tobe printed is positioned, each of said character fields being of thesame size and shape, said character marks of the characters indifiFerent rows being in different positions in their respectivecharacter fields and occupying only a small portion of such fields,

means to sequentially move said rows of characters past a print station,

means to advance a web on which printing can be carried incrementallypast said print station,

buffer storage means operable to store signals representing a row ofcharacters to be printed, and means operable in response to the signalsstored by said buffer storage means to print selected characters in therow of characters at said print station on areas of said web at saidprint station opposite the selected characters as each row of charactersis moved past said print station to thereby print the row of charactersrepresented by the signals stored in said bufier storage means. 26. Acurve plotting apparatus as recited in claim 25 wherein said meansdefining a plurality of rows of characters is a drum defining saidcharacters on the periphery of said drum and said means to move saidcharacters sequentially past the print station comprises means to rotatesaid drum.

27. A curve plotting apparatus comprising: means defining a plurality ofrows of characters, each of said characters having a character field inwhich a character mark adapted to be printed is positioned, each of saidcharacter fields being of the same size and shape, said character marksof characters of different rows being in different positions in theirrespective character fields and occupying only a small portion of suchfields. means to sequentially move said rows of characters past a printstation,

means to advance a web on which printing can be carried outincrementally past said print station in increments equal to a fractionof the length of said character fields,

bufi'er storage means operable to store signals representing a row ofcharacters to be printed,

means operable in response to the signals stored by said bufier storagemeans to print selected characters in the row of characters at saidprint station on areas of said web at said print station opposite theselected characters as each row of characters is moved past said printstat-ion to thereby print the row of characters represented by thesignals stored in said buffer storage means.

28. A curve plotting apparatus comprising:

means defining a plurality of rows of characters, each of saidcharacters having a character field in which a character mark adapted tobe printed is positioned, each of said character fields being of thesame size and shape, the character marks of the characters in a firstone of said rows being positioned in the middle of their respectivecharacter fields and occupying a

1. A CURVE PLOTTING APPRATUS COMPRISING: MEANS DEFINING A PLURALITY OFCHARACTERS, EACH OF SAID CHARACTERS HAVING A CHARACTER FIELD IN WHICH ACHARACTER MARK ADAPTED TO BE PRINTED IS POSITIONED, EACH OF SAIDCHARACTER FIELDS BEING OF THE SAME SIZE AND SHAPE, THE CHARACTER MARK OFEACH OF SAID CHARACTERS HAVING THE SAME SHAPE BUT BEING LOCATED IN ADIFFERENT POSITION IN ITS CHARACTER FIELD, MEANS TO SELECT ONE OF SAIDCHARACTERS, AND MEANS TO PRINT THE CHARACTER MARK OF THE SELECTEDCHARACTER IN A PREDETERMINED AREA ON A MEDIUM, SAID PREDETERMINED AREAHAVING THE SAME SIZE AND SHAPE AS SAID CHARACTER FIELDS AND THECHARACTER MARK OF SAID SELECTED CHARACTER BEING PRINTED IN THE SAMEPOSITION IN SAID PREDETERMINED ARES THAT THE CHARACTER MARK ISPOSITIONED IN THE FIELD OF THE SELECTED CHARACTER.